scratched, then sniffed? exploring the role of chemotaxis in host invasion (730)

Motile bacteria are attracted by certain chemicals and repelled by others, a behaviour that enables them to navigate towards favourable niches for growth and survival. This process – chemotaxis – is used by many plant pathogens, to navigate over the plant surface in order to locate potential entry sites.

Pseudomonas syringae pv. actinidae (Psa) is a destructive pathogen of kiwifruit, that is currently causing severe economic losses in New Zealand and worldwide. Psa is motile, and invades host plant tissues through natural openings (e.g. stomata, lenticels), or via lesions or wounds. It also has an unusally complex chemosensory system, with 43 putative chemoreceptors encoded in its genome.

The goal of this research is to identify the function of individual chemoreceptors, and to explore their role in the colonisation of kiwifruit leaves by Psa.

Methods:

Chemoreceptor deletion strains are currently being generated using allelic exchange by homologous recombination. Wild-type Psa and deletion strains will be fluorescently labelled, and tested using a variety of approaches, including leaf colonisation and capillary assays.

Results:

Progress towards functional characterisation of the fluorescently labelled wild-type and deletion strains will be presented.

Conclusions:

By characterising the chemoreceptors of Psa, this research will provide important insights into how this bacterium recognizes its host.